The present invention relates to a water hydrant or faucet of the type which connects a water supply conduit located inside a building to a hose connection located outside the building.
In such hydrants which are exposed to ambient temperatures below freezing, an automatic drain mechanism must be incorporated or the water left standing in the hydrant will freeze and block the hydrant. In severe conditions, the hydrant can burst due to the expansion of the frozen water. Furthermore, such hydrants are subject to back-siphoning of water from a connected hose when the end of the hose is immersed in a tank of liquid and the pressure in the supply line drops for some reason. Particularly when the hydrant is used for industrial or farming purposes, this back siphoning can draw chemicals or other pollutants into the water supply lines and cause contamination of the potable water therein.
Numerous hydrant and faucet designs have been devised to prevent freeze blockage or damage as well as back-siphoning. Typical so-called freezeless faucets usually incorporate a double valve arrangement. As the hydrant is opened, e.g. by turning a threaded valve stem attached to a circular handle, an drain vent valve closes to block least one drainage vent. Subsequent turns of the handle then open a water supply valve to admit water from the supply conduit into the hydrant and hose bib. In order to shut off the hydrant, the handle is turned in the opposite direction, which closes the water supply valve. Subsequent turning of the handle then opens the drain vent valve which opens the drainage vents to drain any water trapped in the hydrant.
Back-siphoning of liquids from a connected hose is prevented by an anti-siphoning vacuum valve which is typically attached to the hose bib itself. The vacuum valve is generally a spring loaded valve which opens due to water pressure from the supply conduit exerted against the action of the spring. In the event of a drop in water supply pressure, the spring urges the valve closed, thus preventing any liquid from being siphoned from the hose back into the hydrant. Typically, vacuum valves also incorporate air vents which open when the vacuum valve is closed to aid in draining the hydrant.
Many hydrants or faucets incorporate both freezeless and anti-siphoning features. With increased concern for contamination of potable water sources, it is becoming common for water supply companies to require anti-siphoning devices on any hydrant connected to their systems.
Typical prior art anti-siphoning and freezeless hydrants have tended to be intricate mechanisms incorporating many separable parts. In some freezeless hydrants, a dual conduit runs from the water supply valve through the wall to separate hose bib and drain outlets. This necessitates a complex machined part which is expensive to produce in quantity. Other freezeless hydrants have used valve stems with removable drain valve elements which comprise as many as four different parts. Another problem with prior art freezeless hydrants has been that the hydrant can be oriented in a manner which does not permit complete drainage even with an open drain vent.
Yet another problem with such freezeless hydrants is that when the hydrant is shut off with a hose attached, back pressure from the hose and remaining water pressure within the hydrant causes water to spray out of the drainage vents when the drain vent valve is opened. Without some sort of splash guard, it is not uncommon for the person operating the hydrant can get thoroughly soaked.
It is clear then, that a need exists for an anti-siphoning freezeless water hydrant which is simple and inexpensive to produce. Such a hydrant should incorporate as few working parts as possible and should be clearly designed for proper drainage orientation during installation. The hydrant should include an integral splash guard to protect the user from water spraying from the drainage vents.